446 Stainless Steel: Properties and Key Applications
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Table Of Content
Table Of Content
446 stainless steel is classified as an austenitic stainless steel, notable for its high chromium content and the addition of molybdenum, which enhances its resistance to oxidation and corrosion. This steel grade is primarily composed of chromium (24-27%) and nickel (19-22%), with molybdenum (up to 1.5%) as a significant alloying element. The high chromium content provides excellent resistance to oxidation and high-temperature environments, while nickel contributes to its toughness and ductility.
Comprehensive Overview
446 stainless steel is particularly recognized for its exceptional high-temperature strength and oxidation resistance, making it suitable for applications in environments where other stainless steels may fail. Its ability to maintain mechanical properties at elevated temperatures, combined with good weldability and formability, makes it a preferred choice in various industrial applications, especially in the petrochemical and power generation sectors.
Advantages:
- High-Temperature Resistance: Capable of withstanding temperatures up to 1200°C (2192°F) without significant degradation.
- Corrosion Resistance: Excellent resistance to oxidation and scaling in high-temperature environments.
- Durability: Good mechanical properties, including strength and ductility, contribute to its longevity in service.
Limitations:
- Cost: Higher alloy content can lead to increased material costs compared to lower-grade stainless steels.
- Weldability Challenges: While it can be welded, care must be taken to avoid issues such as hot cracking.
- Limited Availability: Not as commonly stocked as other stainless steel grades, which may affect lead times.
446 stainless steel has a strong market position in specialized applications, particularly where high-temperature performance is critical. Its historical significance lies in its development for use in furnace components, heat exchangers, and other high-temperature applications.
Alternative Names, Standards, and Equivalents
| Standard Organization | Designation/Grade | Country/Region of Origin | Notes/Remarks |
|---|---|---|---|
| UNS | S44600 | USA | Closest equivalent to EN 1.4762 |
| AISI/SAE | 446 | USA | Commonly used designation |
| ASTM | A240 | USA | Standard specification for stainless steel plates |
| EN | 1.4762 | Europe | Minor compositional differences to be aware of |
| JIS | SUS446 | Japan | Equivalent grade with similar properties |
| GB | 00Cr25Ni20 | China | Comparable grade with slight variations |
The differences between these equivalent grades often lie in minor compositional variations that can affect performance in specific environments. For instance, while both UNS S44600 and EN 1.4762 offer similar high-temperature resistance, the specific alloying elements and their percentages can influence corrosion resistance and mechanical properties.
Key Properties
Chemical Composition
| Element (Symbol and Name) | Percentage Range (%) |
|---|---|
| Cr (Chromium) | 24.0 - 27.0 |
| Ni (Nickel) | 19.0 - 22.0 |
| Mo (Molybdenum) | 0.5 - 1.5 |
| C (Carbon) | ≤ 0.03 |
| Mn (Manganese) | ≤ 1.0 |
| Si (Silicon) | ≤ 1.0 |
| P (Phosphorus) | ≤ 0.045 |
| S (Sulfur) | ≤ 0.03 |
The primary role of chromium in 446 stainless steel is to enhance corrosion resistance and oxidation resistance at elevated temperatures. Nickel contributes to the steel's toughness and ductility, while molybdenum improves resistance to pitting and crevice corrosion, particularly in chloride environments.
Mechanical Properties
| Property | Condition/Temper | Typical Value/Range (Metric - SI Units) | Typical Value/Range (Imperial Units) | Reference Standard for Test Method |
|---|---|---|---|---|
| Tensile Strength | Annealed | 515 - 690 MPa | 75 - 100 ksi | ASTM E8 |
| Yield Strength (0.2% offset) | Annealed | 205 - 310 MPa | 30 - 45 ksi | ASTM E8 |
| Elongation | Annealed | 40 - 50% | 40 - 50% | ASTM E8 |
| Hardness (Rockwell B) | Annealed | 85 - 95 HRB | 85 - 95 HRB | ASTM E18 |
| Impact Strength (Charpy V-notch) | -20°C | 40 J | 30 ft-lbf | ASTM E23 |
The combination of high tensile and yield strength, along with good elongation, makes 446 stainless steel suitable for applications that require structural integrity under mechanical loading. Its impact strength at low temperatures also ensures reliability in colder environments.
Physical Properties
| Property | Condition/Temperature | Value (Metric - SI Units) | Value (Imperial Units) |
|---|---|---|---|
| Density | Room Temperature | 7.8 g/cm³ | 0.283 lb/in³ |
| Melting Point/Range | - | 1400 - 1450 °C | 2552 - 2642 °F |
| Thermal Conductivity | Room Temperature | 25 W/m·K | 17.3 BTU·in/(hr·ft²·°F) |
| Specific Heat Capacity | Room Temperature | 500 J/kg·K | 0.119 BTU/lb·°F |
| Electrical Resistivity | Room Temperature | 0.73 µΩ·m | 0.0000013 Ω·in |
| Coefficient of Thermal Expansion | 20 - 100 °C | 16.5 x 10⁻⁶ /K | 9.2 x 10⁻⁶ /°F |
The density of 446 stainless steel indicates its robustness, while its melting point signifies its suitability for high-temperature applications. The thermal conductivity and specific heat capacity are critical for applications involving heat exchangers, where efficient heat transfer is essential.
Corrosion Resistance
| Corrosive Agent | Concentration (%) | Temperature (°C/°F) | Resistance Rating | Notes |
|---|---|---|---|---|
| Sulfuric Acid | 10-20 | 25/77 | Fair | Risk of pitting |
| Chlorides | 3-5 | 60/140 | Good | Susceptible to pitting |
| Sea Water | - | 25/77 | Excellent | Good resistance |
| Hydrochloric Acid | 5-10 | 25/77 | Poor | Not recommended |
446 stainless steel exhibits excellent resistance to various corrosive environments, particularly in high-temperature applications. Its performance in chloride-rich environments is noteworthy, although it is susceptible to pitting corrosion. Compared to grades like 304 and 316 stainless steel, 446 offers superior oxidation resistance but may not perform as well in reducing environments or in the presence of strong acids.
Heat Resistance
| Property/Limit | Temperature (°C) | Temperature (°F) | Remarks |
|---|---|---|---|
| Max Continuous Service Temp | 1200 | 2192 | Optimal for high-temperature applications |
| Max Intermittent Service Temp | 1300 | 2372 | Short-term exposure only |
| Scaling Temperature | 1150 | 2102 | Begins to oxidize significantly |
| Creep Strength Considerations Begin | 800 | 1472 | Creep may become a concern |
446 stainless steel maintains its mechanical properties at elevated temperatures, making it ideal for applications such as furnace components and heat exchangers. Its oxidation resistance allows it to perform well in environments where other steels may fail due to scaling or oxidation.
Fabrication Properties
Weldability
| Welding Process | Recommended Filler Metal (AWS Classification) | Typical Shielding Gas/Flux | Notes |
|---|---|---|---|
| TIG | ER446 | Argon | Preheat recommended |
| MIG | ER446 | Argon + 2% O₂ | Good for thin sections |
| Stick | E446 | - | Requires careful control |
Weldability of 446 stainless steel is generally good, but it requires careful attention to avoid hot cracking. Preheating before welding can help mitigate this risk, and post-weld heat treatment may be necessary to relieve stresses.
Machinability
| Machining Parameter | [446 Stainless Steel] | Benchmark Steel (AISI 1212) | Notes/Tips |
|---|---|---|---|
| Relative Machinability Index | 30% | 100% | Requires slower speeds |
| Typical Cutting Speed (Turning) | 20 m/min | 60 m/min | Use carbide tools |
Machinability of 446 stainless steel is lower than that of more common grades like AISI 1212. It is advisable to use carbide tooling and slower cutting speeds to achieve optimal results.
Formability
446 stainless steel exhibits moderate formability. Cold forming is possible, but care must be taken to avoid work hardening. Hot forming is preferred for complex shapes, and recommended bend radii should be adhered to in fabrication.
Heat Treatment
| Treatment Process | Temperature Range (°C/°F) | Typical Soaking Time | Cooling Method | Primary Purpose / Expected Result |
|---|---|---|---|---|
| Annealing | 1050 - 1150 / 1922 - 2102 | 1 - 2 hours | Air | Relieve stresses, improve ductility |
| Solution Treatment | 1000 - 1100 / 1832 - 2012 | 1 hour | Water | Enhance corrosion resistance |
During heat treatment, 446 stainless steel undergoes metallurgical transformations that enhance its microstructure, improving its mechanical properties and corrosion resistance.
Typical Applications and End Uses
| Industry/Sector | Specific Application Example | Key Steel Properties Utilized in this Application | Reason for Selection (Brief) |
|---|---|---|---|
| Power Generation | Boiler Tubes | High-temperature strength, oxidation resistance | Essential for high-efficiency systems |
| Petrochemical | Furnace Components | Corrosion resistance, durability | Critical for long-term operation |
| Aerospace | Exhaust Systems | High-temperature performance | Required for extreme conditions |
Other applications include:
* Heat exchangers
* Industrial furnaces
* Chemical processing equipment
The selection of 446 stainless steel for these applications is primarily due to its ability to withstand high temperatures and corrosive environments, ensuring reliability and longevity.
Important Considerations, Selection Criteria, and Further Insights
| Feature/Property | 446 Stainless Steel | 304 Stainless Steel | 316 Stainless Steel | Brief Pro/Con or Trade-off Note |
|---|---|---|---|---|
| Key Mechanical Property | High tensile strength | Moderate tensile strength | Moderate tensile strength | 446 offers superior high-temp performance |
| Key Corrosion Aspect | Excellent oxidation resistance | Good general corrosion resistance | Better resistance to chlorides | 446 is less effective in reducing environments |
| Weldability | Moderate | Good | Good | 446 requires more care during welding |
| Machinability | Moderate | Good | Good | 446 is harder to machine than 304/316 |
| Formability | Moderate | Good | Good | 446 is less formable than 304/316 |
| Approx. Relative Cost | Higher | Lower | Moderate | Cost can be a deciding factor in selection |
| Typical Availability | Limited | Widely available | Widely available | Availability may affect project timelines |
When selecting 446 stainless steel, considerations such as cost-effectiveness, availability, and specific application requirements must be taken into account. Its unique properties make it suitable for niche applications where high-temperature performance is critical, but its higher cost and limited availability may necessitate careful planning and sourcing strategies.
In summary, 446 stainless steel is a high-performance material that excels in demanding environments, making it a valuable choice for industries requiring durability and reliability under extreme conditions.
Data Sources & Verification
Chemical composition and mechanical property values on this page are compiled from published material standards and cross-referenced against the equivalent designations listed above (UNS S44600, ASTM A240, EN 1.4762, JIS SUS446, GB 00Cr25Ni20). Values are typical or nominal and vary with product form, thickness, and heat treatment; confirm against the governing standard and mill test certificate before design or procurement use.
Design tools: Working with this grade structurally? Use our free Load Capacity Calculator, Span Calculator, and Steel Beam Calculator. Estimate material weight with our steel weight calculators.
Technically reviewed by Dr. Zhang Zhiwei — former Senior Technical Specialist, Baosteel Group; member, Chinese Society for Metals. How we compile our data · spotted an error? Tell us and we will review it.
12 comments
This is a very detailed breakdown of 446 stainless steel, especially regarding its oxidation resistance at 1200°C. I’m currently working on a technical procurement audit for a high-temperature processing plant and found your comparison table with 310/316 grades incredibly useful for our material selection process. Since we are looking for reliable partners in the current 2026 market, I’ve been researching how different industrial sectors handle their regulatory and transparency verification. While checking some service providers, I came across this review regarding operational legitimacy: https://guiadenovibetbrasil.com/ — do you think applying similar transparency standards and “official regulatory verification” is becoming a mandatory trend for specialized steel suppliers as well, or is the industry still mostly relying on traditional ISO certifications?
I really appreciate the technical depth here, especially the part about the 1200°C oxidation resistance—it’s a game-changer for our upcoming furnace component specs. However, I’m currently stuck on the business side of things; as we look into scaling our industrial supply operations, I’ve been comparing how different high-tech sectors handle their infrastructure and “hidden” operational costs. Since this article touched on the limited availability and cost-effectiveness of 446 steel, it made me wonder: has anyone here tried to model long-term scaling costs for technical platforms using a similar breakdown as seen in this guide on iGaming software cost https://igaming-solution.com/guides/igaming-software-cost/? I’m trying to figure out if the shift from setup fees to revenue-based models is becoming a standard in B2B industrial niches too, or if we should stick to traditional licensing for our supply chain software. Any thoughts on how these pricing models compare when you’re dealing with niche, high-value materials?
Vielen Dank für die detaillierte Analyse der Eigenschaften von 446-Edelstahl, insbesondere die Daten zur Oxidationsbeständigkeit sind für unsere aktuellen Projektkalkulationen sehr wertvoll. Da wir uns im Bereich der industriellen Compliance bewegen, achten wir bei der Auswahl von Partnern und Materialien immer stärker auf die regulatorische Transparenz und Lizenzierung, ähnlich wie es in anderen hochregulierten Märkten der Fall ist. In diesem Zusammenhang habe ich eine Frage zur Verifizierung von Standards: Gibt es eine zentrale Datenbank für Materialzertifikate, die so transparent aufgebaut ist wie die offizielle Lizenzprüfung für Betreiber in Brasilien unter https://guiadebetnacionalbrasil.com , wo man die staatlichen Portarien und die technische Konformität direkt einsehen kann? Mich würde brennend interessieren, ob es für die Stahlindustrie im Jahr 2026 ein ähnlich zugängliches Register für ISO-Zertifikate gibt, um die Authentizität der Chargen schneller zu prüfen.
Excelente análisis técnico sobre el acero 446, especialmente útil la tabla de conductividad térmica para el cálculo de intercambiadores. Estamos evaluando este grado para un proyecto de montaje industrial en la zona de Madrid y me surge una duda técnica: ¿han notado variaciones significativas en la resiliencia del material tras ciclos prolongados a 800°C en ambientes con presencia de azufre?
Por otro lado, como planeamos desplazar a nuestro propio equipo de soldadores especializados para la fase de instalación en España, estamos revisando la logística administrativa para que operen legalmente. He visto este recurso para la gestión de documentos en la capital https://e-residence.com/nie-spain-online/madrid/ y me gustaría saber si alguien tiene referencias sobre si los tiempos de respuesta para empresas de ingeniería suelen ser los que indican ahí o si conviene tramitarlo directamente por otra vía B2B. ¡Gracias de antemano!
Thanks for the detailed breakdown of the 446 grade’s thermal expansion properties; it’s crucial for the heat exchanger specs I’m currently reviewing. I noticed you mentioned the limited availability in some regions—since our firm is looking to oversee the installation of these components for a client in Iberia, we’re actually prepping the technical team for on-site work there. On a side note, does anyone here have experience with the speed of administrative processing for foreign contractors in that region? I was looking at this resource for getting the necessary ID numbers for our engineers https://e-residence.com/de/nie-spain-online/ and wondered if this is the standard path you’d recommend for a project team, or if there’s a more direct B2B route? Any insight on both the material sourcing and the logistics would be greatly appreciated!